Rectangular metal cathode ray tube



Feb. 26, 1957 s. J. KOCH ETAL 2,782,953

RECTANGULAR METAL CATHODE RAY TUBE Filed March 15, 1950 2 Sheets-Sheet l 4 i 3 5 INVENTORS STANLEY .1. KOCH BY ROBERTE. RUTHERFORD Feb. 26, 1957 5. J. KOCH EI'AL RECTANGULAR METAL CATHODE RAY TUBE 2 Sheets-Sheet 2 Filed March 15. 1950 M w m m m mmm Xwu J Y n L .M M M Fig. 6

United States Fatent Of 2,782,953 Fatented Feb. 26, 1957 RECTANGULAR METAL CATHODE RAY TUBE Stanley J. Koch, Clifton, and Robert E. Rutherford, Nutley, N. J., assignors to Allen B. Du Mont Laboratories, Inc., Clifton, N. l, a corporation of Delaware Application March 13, 1950, Serial No. 149,342

1 Claim. (Cl. 220-23) entire picture on a cathode ray tube having a circular screen, it has been necessary to use only a rectangular portion thereof with the corners of the rectangular picture substantially at the edge of the circular screen. Conversely the tube may be operated so that a portion of the transmitted picture covers a large part or even the whole of the circular screen by suitable adjustment of e the scanning apparatus of the receiver. In this latter event not all of the original picture is reproduced, since portions extend beyond the viewing surface of the tube. A compromise, therefore, between seeing the entirepicture and using most or all of the screen, has been made. However, a tube having a rectangular viewing surface has long been desirable.

In recent years cathode ray tubes have been made having a glass neck portion, a glass viewing screen and a metal frusto-conical portion. One of the fundamental problems in the production of such tubes in which there is a relatively large glass to metal seal area is that of obtaining a metal having the same temperature coefiicient of expansion as that of the glass. One such metal, and that which is popularly used, is an alloy of iron and chromium known and available on the market as 446 Chrome Iron, in which chromium comprises approximately 26% to 30% of a volume of the metal. This alloy may be hot rolled into sheets. It is not sutliciently malleable to be pressed or drawn into the shape required for use in a cathode ray tube. It is possible, however, to spin pieces cut from the sheets into circular cones.

Heretofore there has been no known method of pro ducing a metal cathode ray tube having a rectangular face, and no structure has been known producing a commercially satisfactory product. The rectangular cone portion of the tube could neither be spun nor pressed out of the chrome iron.

Consequently, it is an object of this invention to provide an improved cathode ray tube and method of manufacturing such tube.

Another object is to provide a commercially practical metal cathode ray tube having an approximately rectangular face or viewing surface.

Other objects will be apparent after a study of the following specification, claim and drawings, in which:

Figure 1 is a perspective view of a cathode ray tube constructed in accordance with the invention;

Figure 2 shows the contour of the face plate of the tube of Figure 1;

Figure 3 is a side elevational view of the rectangular metal cone portion of the tube;

Figure 4 is a cross sectional view of the frustoconical die and the metal cone;

Figure 5 is a front or open end view of a circular metal cone showing preferred pressure points;

Figure 6 is an exploded view of the tool and die and resulting rectangular cone involved in one step of the method herein disclosed; and

Figure 7 is a view of the metal blank showing another step in the process.

Referring now to Figure 1, it may be seen that the metal rectangular cathode ray tube comprises a cone portion 11, a face plate 12 and a neck portion 13. The substantially rectangular face plate is shown in the front view of Figure 2. The cone portion 11 is made of a chrome iron alloy having the same temperature coeflicient of expansion as the glass face plate 12, in order that there may be an airtight seal between the edge of the glass and the rim 14 of the cone. The electron gun structure is mounted in the usual way within the neck portion 13. The face plate 12 is the viewing surface for the tube.

The rectangular cone portion 11 is formed or made in the following way. A circular disc of chrome iron has an inner circular opening of desired radius of for instance, approximately 2% so as to be joined eventually to the neck portion 13 of a cathode ray tube. This disc is then formed in the shape of the frustum of a circular cone by spinning on a lathe and forcing the annular portions between the inner and outer edges of the disc to conform to the contour of a circular conical die 16 shown in cross sectional representation in Figure 4. The circular cone identified at this stage by the numeral 111 has a rim 114 formed at the outer open end thereof as shown in Figure 4. This rim 114 is formed in the manner as heretofore known, so that the glass face plate of the tube may be sealed thereto.

The outer or open end portion of the cylindrical cone 111 next is subjected to a bending operation. Although we do not wish to be limited to any theoretical explanation, it appears that the spinning process increases the ductility of this 446 Chrome Iron thereby making it possible to bend rectangular-faced cones from circular cones. Preferably pressure for such bending operation is applied radially outwardly at four corners in the directions as shown by the arrows in Figure 5. These pressure points conform to the corners of the rectangular face plate or viewing surface having the approximate width to height ratio of 4:3. No pressure is applied to the lower constricted portion of the cone 11 so that this portion remains circular in cross section. The rim portion 114 of the cone 111 is bent carefully into the approximately rectangular shape desired, as illustrated in Figures 1 and 2.

The tool and die apparatus as shown in Figure 6 may be used in the bending operation. The die member 31 may have the shape as shown in Figure 6, being circular in cross section at the lower constricted portion thereof, with protruding portions at the corners of the upper portion thereof to exert pressure radially outwardly at the points shown in Figure 5. Thus when the cone is removed from the die 32 after being subjected to the pressure of the cooperating die member 31, it is in the desired rectangular form at the open end and circular at the inner or constricted end.

.In order to insure the circularity of the constricted end of the cone 11 in spite of the deformation of the outer end of the cone 11, it has been found desirable to shape the cone 111 originally so that the in-turned flange at the constricted end will be an annular section of a fiat disc instead of the frustum of a wide angle cone which is used in the prior art circular cross-section metal tubes and is shown in Figure 4. The necessity for strengthening the constricted end of the cone arises from the fact that the neck 13 is joined to the cone 11 by a butt weld which has comparatively little strength. Therefore, atmospheric pressure on the substantially fiat sides of the cone 11, after the tube has been evacuated, may hens. he QP l P d. of. h ewe l su ieien ly to break the glass-to-rnetal seal at that point.

Forbetter results it is desirable that the 1 14 be somewhat thicker h n e si Po io o he som as for instance, .l25 and .075. A glass face plate ha i he n o r onf m n to d e ame shape as the'rim 14 of the rectangular cone may then be placed thereon and heated to cause the glass to melt and adhere by sealing ther eto. This sealing operation is shown in i ure. i Pre e ed th t a p ur li heat h l lh ts. 2.8 e us d s as o euhl e he i n i e els? f; e lass Plate t a hhi orm. eat n he sheet he eh'eumfer n e he eefi. The hhrtlh r. Qt. s' l h ehts h us d i not a er t eal. but i Th ie, wit in @plah The ed es. i. h ove eateh 01 warsl y. from. he c er as to orm round. yrians. o h 19 hdi l y 'eh nsver of. th reet ns lar;

of air pressure than are circular tubes. Al. the, Same time, the o ers being. a r. harp. a e. su ject.

9. ie ease; tre s s. C n e uen ly he glass one mus e. made eeedih lyh e n h et b as de-. scrib d iieljeih by. contrast, the metalcone is-sufiiciently,

s i lslte. hea l gh l at e i pressure, e h e ntv strong tg retainit s primary or general shape. Furthermore; the cgrners of the rectangular metal cone are. hoes. T etetor lth u h he. glass ace pl -ls s eaker o o ees a l ed. a on t e i nal D t-Figure. 2, thehgetalcpne 1; 1; is stronger at this pOint amiable. ojres st'th respect to f lih 9 9 i Yea eehs ct ngular metal cone e hee. thee-P a .12.-e .0pe o-f m a rigid;

l iq le thy-.thh sq e. ame or. imi r ize.

The; to low hs. teps a nvolved in maki g. ompl I ;at .11 1 is fabricated and, thereafter formed by. s p l e bending into the rectangular shapeasindicated tgll Ths eet er he. ey dIieals a s neck portion .12? hi a l qdtflq the ma ler Q tr d. end, of the-cone, Tcgaeeomplishthis the cone 11 and the neckporti0n13 be mounted on a lathe and brought together-in image qt: e t hi h mel s t edge. of the heck; 11}. jqin ing -t;hgcone so that the two arev sealed, and, formed.

into an airtight single or unitary piece. The face-plate. lg may-then be attached to the open end, of thecone 1.1,

tqrces. The, face plate 12;is stronger with I s applied in the direction indicated-by. he 9m -..h eorr spondi o P i s ete h sa able. W hstahdthe m o es. as p t-v rect 11a metal cathode ray tubes. The circularmetal:

preferably by mounting the cone in a vertical position,

that is with its rim 14 uppermost, and placing the face plate 12 in position to rest; on the rim. A plurality of heating means 28, positioned about the circumference of the rim 14 heats the rim, melting the edge of the face plate 12 and forming an airtight seal.

A tube blank for a rectangular cathode ray tube has thus been formed. The fluorescent particles may be applied to the glass face plate 12 or screen of the tube and the gun structure mounted within the neck portion B, in accordance with well known methods and principles as used in prior art cylindrical tubes.

A rectangular metal cathode ray tube'has been. formed with a viewing surface having the 4:3 width to height ratio to accommodate the transmitted television picture. Essentially none of the picture is lost. while at the same time, essentially the entire screen of the tube may be used. A rectangular tube having arirn widthiotf 1.6"

nd he gh of 12. will produce a; picturehavingtha-sam sizeas prior art circular screen'tubes having adiametcr of 20".

Whilemodifica ims ill occur to. those skilled in the f ithe 5.601 8 of: hein ention is.,defined in-the. following claim.

What. is claime i A television tube.- envelope comprising; a one. piece continuo s. shee metaltapering body, the. lower end. of said bodyhaving, a circular opening therein, the upper nd. of;- said body being .openandi the. walls about said pening. defining; an opening substantially; rectangular: in outline, the freemarginal. edges of said wallsv defining said opening beingtormedinto a seating ledge of, sub: stantially rectangular configuration, each of. the four sides of: the substantiallyrectangular seating. ledgebeingup- Wardlyjcurved.longitudinally thereof andcoacting witheachother to forma convexly: curved. seat for'receiving.

a longitudinally and. transversely COILVCXlY', curved; substantially rectangular viewing screen.

References Cited in the file of thispatent UNITED STATES PATENTS 11,112,474 Bowie Dec. 6, 1938 D. 11113.19. Bowie, Oct. 5, I939 1,613,059; Lammine. Apr. 5, 1927 .2297356 Lindgr n Dec 12,, 933 15,96 ,22 Hje t r J ly '1; 1934 2.986.488 Batie July 6, 1937' 2,100,901 Harries Nov. 30, 1937' ,132,733 Gold ark .1938 2.17 .82 1.939- M89192; I939 2,124 5 1.1 1940 2,.2. ..7. 9 0 2,232,Q28 1941 2,256,108 19.4.1 2.2 3.990. 941 2,295,307 Power Sept. 22, 1942 29.3.9163 Cal son n- 25; 1944 .363959. 1944 2,378,982 June 26, 1945 2,4,5,5,,8 28,. Thielet alc- 19 2. 22.25 r -is. s p 1-2. 19.5 FOREIGN PATENTS.

France June 20; 1919 

